RPS assisted RF plasma source for semiconductor processing

ABSTRACT

Embodiments of the disclosure generally relate to a hybrid plasma processing system incorporating a remote plasma source (RPS) unit with a capacitively coupled plasma (CCP) unit for substrate processing. In one embodiment, the hybrid plasma processing system includes a CCP unit, comprising a lid having one or more through holes, and an ion suppression element, wherein the lid and the ion suppression element define a plasma excitation region, a RPS unit coupled to the CCP unit, and a gas distribution plate disposed between the ion suppression element and a substrate support, wherein the gas distribution plate and the substrate support defines a substrate processing region. In cases where process requires higher power, both CCP and RPS units may be used to generate plasma excited species so that some power burden is shifted from the CCP unit to the RPS unit, which allows the CCP unit to operate at lower power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. provisional patent application Ser.No. 61/934,325, filed Jan. 31, 2014, which is herein incorporated byreference

BACKGROUND

Field

Embodiments of the present disclosure generally relate to an apparatusand method for processing gases and substrates in a semiconductorsubstrate process chamber.

Description of the Related Art

In the fabrication of semiconductor devices, plasma chambers commonlyare used to perform various fabrication processes such as etching,chemical vapor deposition (CVD), and sputtering. Generally, a vacuumpump maintains a very low pressure within the chamber while a mixture ofprocess gases continuously flows into the chamber and an electricalpower source excites the gases into a plasma state. The constituents ofthe process gas mixture are chosen to effect the desired fabricationprocess

It has been observed that some of conventional plasma processing chamberdesigns in which the plasma is generated between two parallel electrodes(i.e., capacitive coupling plasma) can cause unwanted particlecontamination on a substrate surface due to ion bombardment of theelectrodes. In deposition processes that require a higher RF input power(over 550 W), once the plasma has been created, a high self-inducednegative DC bias is also naturally established at the powered electrode.The electrical potential difference between the plasma and theself-induced negative DC bias forms a sheath voltage at or near thepowered electrode. This sheath voltage causes positive ions within theplasma to accelerate toward the powered electrode, resulting in ionbombardment of the powered electrode. In instances where the poweredelectrode includes a protective coating layer, a portion of theprotective coating layer may flake off as a result of the ionbombardment after a long period of time and contaminate the substratesurface. While a lower RF input power can be used to generate the plasma(and thus reduce particle contamination), the film deposition rate willbe decreased, which in turn lowers the process yield.

Therefore, there is a need in the art for an apparatus and process thateffectively reduces the generation of contaminating particles on thesubstrate surface and maintains high process yield.

SUMMARY

Embodiments of the disclosure relate to a hybrid plasma processingsystem combining a primary plasma source, such as capacitively coupledplasma (CCP) source or inductively coupled plasma (ICP) source, and asecondary plasma source, such as remote plasma source (RPS). In oneembodiment, a substrate processing system is provided. The systemincludes at least one primary plasma source unit, comprising a lidhaving one or more through holes, and an ion suppression element,wherein the lid and the ion suppression element define a plasmaexcitation region, and a remote plasma source (RPS) unit coupled to theat least one primary plasma source unit, wherein the one or more throughholes of the lid are configured to fluidly connect a gas outlet of theRPS unit to the plasma excitation region, and a gas distribution platedisposed between the ion suppression element and a substrate support,wherein the gas distribution plate and the substrate support defines asubstrate processing region.

In another embodiment, a substrate processing system includes a tandemprocessing chamber and a RPS unit coupled to the tandem processingchamber. The tandem processing chamber includes first and secondprocessing chambers. The first processing chamber includes a first lidhaving a first gas inlet and a plurality of first holes surrounding thefirst gas inlet, wherein the first gas inlet is in fluid communicationwith a first gas source, a first ion suppression element arrangedparallel to the first lid, wherein the first ion suppression element andthe first lid define a first plasma excitation region, and a first gasdistribution plate disposed between the first ion suppression elementand a first substrate support, wherein the first gas distribution plateand the first substrate support defines a first substrate processingregion within the first processing chamber. The second processingchamber is disposed adjacent to the first processing chamber andincludes a second lid having a second gas inlet and a plurality ofsecond holes surrounding the second gas inlet, wherein the second gasinlet is in fluid communication with the first gas source, and a secondion suppression element arranged parallel to the second lid, wherein thesecond ion suppression element and the second lid define a second plasmaexcitation region, and a second gas distribution plate disposed betweenthe second ion suppression element and a second substrate support,wherein the second gas distribution plate and the second substratesupport defines a second substrate processing region within the secondprocessing chamber. The RPS unit includes a gas inlet and an gas outlet,wherein the gas inlet is in fluid communication with a second gassource, and the gas outlet is in fluid communication with the pluralityof first holes and the plurality of second holes through a first gaspassageway and a second gas passageway, respectively.

In yet another embodiment, a substrate processing system comprises afirst processing chamber and a second processing chamber. The firstprocessing chamber comprises a first primary plasma source unit,comprising a first lid having one or more through holes, wherein thefirst lid is in fluid communication with a first gas source, and a firstion suppression element, wherein the first lid and the first ionsuppression element define a first plasma excitation region, and a firstremote plasma source (RPS) unit coupled to the first primary plasmasource unit, wherein the first RPS unit is in fluid communication with afirst external gas source, and a first gas distribution plate disposedbetween the first ion suppression element and a first substrate support,wherein the first gas distribution plate and the first substrate supportdefines a first substrate processing region. The second processingchamber comprises a second primary plasma source unit, comprising asecond lid having one or more through holes, wherein the second lid isin fluid communication with a second gas source, and a second ionsuppression element, wherein second first lid and the second ionsuppression element define a second plasma excitation region, a secondremote plasma source (RPS) unit coupled to the second primary plasmasource unit, wherein the first RPS unit is in fluid communication with afirst external gas source, and a second gas distribution plate disposedbetween the second ion suppression element and a second substratesupport, wherein the second gas distribution plate and the secondsubstrate support defines a second substrate processing region.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a simplified cross-sectional view of an exemplary hybridplasma processing system according to embodiments of the disclosure.

FIG. 2 is a simplified perspective view of an exemplary hybrid plasmaprocessing system according to embodiments of the disclosure.

FIG. 3 is a simplified schematic of the gas flow paths of a pair of gasmixtures through the hybrid plasma processing system of FIG. 1 accordingto embodiments of the disclosure.

FIG. 4 is a simplified cross-sectional view of another exemplary hybridplasma processing system according to embodiments of the disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments of the disclosure relate to a hybrid plasma processingsystem combining a primary plasma source, such as capacitively coupledplasma (CCP) source or inductively coupled plasma (ICP) source, and asecondary plasma source, such as remote plasma source (RPS). The primaryplasma source may be positioned adjacent to a substrate processingregion and the secondary plasma source may be positioned further awayfrom the substrate processing region. In one embodiment, the primaryplasma source is positioned between the substrate processing region andthe secondary plasma source. Depending upon process requirements, theprimary plasma source and the secondary plasma source may subsequentlyturn on in any desired order for substrate processing. Alternatively,either the primary plasma source or the secondary plasma source isturned on for substrate processing. In cases where RPS and CCP are usedfor plasma generation and substrate processing, the RPS shares orrelieves the power load of the CCP, thereby reducing ion bombardment ofthe powered electrode in the CCP to a lesser extent and allowing layersto be deposited/treated at lower temperatures with less particlecontamination to the substrate surface.

While CCP unit is described in this disclosure as an example for theprimary plasma source, any plasma source using low-pressure dischargesuch as inductively coupled plasma (ICP) source, or using atmosphericpressure discharge such as capacitive discharge, or any other suitableplasma source can be used interchangeably in embodiments describedherein. Details of the disclosure and various implementations arediscussed below.

Exemplary Chamber Hardware

FIGS. 1 and 2 show cross-sectional and perspective views, respectively,of an exemplary hybrid plasma processing system 100 according toembodiments of the disclosure. The hybrid plasma processing system 100generally includes a capacitively coupled plasma (CCP) unit 102 and aremote plasma source (RPS) unit 114 coupled to the CCP unit 102. Thehybrid plasma processing system 100 may hold an internal pressuredifferent than the outside world. For example, the pressure inside thehybrid plasma processing system 100 may be about 10 mTorr to about 20Torr.

The CCP unit 102 functions to generate a first plasma source inside thehybrid plasma processing system 100. The CCP unit 102 may include a lid106 and an ion suppression element 110 disposed relatively below the lid106. The lid 106 and the ion suppression element 110 may be made ofhighly doped silicon or metal, such as aluminum, stainless steel, etc.The lid 106 and the ion suppression element 110 may be coated with aprotective layer comprising alumina or yttrium oxide. In someembodiments, the lid 106 and the ion suppression element 110 areelectrically conductive electrodes that can be electrically biased withrespect to each other to generate an electric field strong enough toionize gases between the lid 106 and the ion suppression element 110into a plasma. A plasma generating gas mixture may be supplied to theCCP unit 102 from a gas source 137 through a gas inlet 107. Anelectrical insulator 108 may be disposed between the lid 106 and the ionsuppression element 110 to prevent them from short circuiting when aplasma is generated. The exposed surfaces of the lid 106, insulator 108,and the ion suppression element 110 generally define a plasma excitationregion 112 in the CCP unit 102.

A power supply 140 is electrically coupled to the CCP unit 102 toprovide electric power to the lid 106 and/or ion suppression element 110to generate a plasma in the plasma excitation region 112. The powersupply 140 may be configured to deliver an adjustable amount of power tothe CCP unit 102 depending on the process performed. The power supply140 is operable to create an adjustable bias voltage in the ionsuppression element 110 to adjust an ion concentration in the activatedgas passing from the plasma excitation region 112 to the gas reactionregion 130. In deposition processes for example, the power delivered tothe CCP unit 102 may be adjusted to set the conformality of thedeposited layer. Deposited dielectric films are typically more flowableat lower plasma powers and shift from flowable to conformal when theplasma power is increased. For example, an argon containing plasmamaintained in the plasma excitation region 112 may produce a moreflowable silicon oxide layer as the plasma power is decreased from about1000 Watts to about 100 Watts or lower (e.g., about 900, 800, 700, 600,or 500 Watts or less), and a more conformal layer as the plasma power isincreased from about 1000 Watts or more (e.g., about 1000, 1100, 1200,1300, 1400, 1500, 1600, 1700 Watts or more). As the plasma powerincreases from low to high, the transition from a flowable to conformaldeposited film may be relatively smooth and continuous or progressthrough relatively discrete thresholds. The plasma power (either aloneor in addition to other deposition parameters) may be adjusted to selecta balance between the conformal and flowable properties of the depositedfilm.

In one embodiment, plasma generating gases may travel from a RPS unit114 through a gas inlet 116 into the plasma excitation region 112. TheRPS unit 114 functions to generate a second plasma source inside thehybrid plasma processing system 100. The RPS unit 114 may include a tube117 where a plasma of ions, radicals, and electrons is generated. Thetube 117 may have a gas inlet 119 disposed at one end of the tube 117and a gas outlet 121 disposed at the other end of the tube 117 opposingthe gas inlet 119. The gas inlet 119 is coupled to a gas source 123while the gas outlet 121 is in fluid communication with the plasmaexcitation region 112. The RPS unit 114 may be coupled to an energysource (not shown) to provide an excitation energy, such as an energyhaving a microwave frequency, to the RPS unit 114 to excite the processgas traveling from the gas source 123 into a plasma. The plasmagenerating gases from the RPS unit 114 may be used to strike a plasma inthe plasma excitation region 112, or may maintain a plasma that hasalready been formed in the plasma excitation region 112. In someembodiments, the plasma generating gases may have already been converted(or at least partially converted) into plasma excited species in the RPSunit 114 before traveling downstream though the gas inlet 116 to the CCPunit 102. The RPS plasma excited species may include ionically-chargedplasma species as well as neutral and radical species. The plasma may beformed in the RPS unit 114 using a microwave, RF, or thermal approach.When the plasma excited species reach the plasma excitation region 112,they may be further excited in the CCP unit 102, or pass through theplasma excitation region 112 without further excitation. In someoperations, the degree of added excitation provided by the CCP unit 102may change over time depending on the substrate processing sequenceand/or conditions.

In general, plasma sources generated by, for example, an energeticexcitation of gaseous molecules consisting of a plasma of charged ions,radicals, and electrons. In some processes where radicals of a plasmaare desirable (as they react in a much more desirable manner withsilicon or polysilicon material on a substrate than ions or a mixture ofradicals and ions), an appropriate ion filter 113, such as electrostaticfilters, wire or mesh filters, or magnetic filters, may be used betweenthe RPS unit 114 and the CCP unit 102 to eliminate the majority orsubstantially all of the ions of the plasma such that only radicals ofthe plasma flow through the CCP unit 102 and react with silicon orpolysilicon material on the substrate, thereby obtaining a greaterselectivity of processing of silicon or polysilicon material than othermaterial (e.g., silicon oxide) on the substrate. In cases where RPSradicals flow through the CCP unit 102, the CCP unit 102 may be turnedon with small amount power to boost radical regeneration to compensateradical loss due to the flow path, or to change radical composition byusing different RF frequency and other parameters. Alternatively, theelectrodes of the CCP unit 102 may not be powered so that the radicalsof the plasma from the RPS unit 114 bypass the CCP unit 102 to avoid orminimize undesired reaction occurred in the plasma excitation region112.

The plasma generating gases and/or plasma excited species may passthrough a plurality of through holes 115 in the lid 106 for a moreuniform delivery into the plasma excitation region 112. The filmuniformity on the substrate can also be tuned by controlling thecenter-to-edge distribution of the plasma generating gases and/or plasmaexcited species through the holes in the lid. Exemplary configurationsinclude having the gas inlet 116 open to a gas supply region 120partitioned from the plasma excitation region 112 by the lid 106 so thatthe gases/species flow through the holes 115 in the lid 106 into theplasma excitation region 112. Structural and operational features may beselected to prevent significant backflow of plasma from the plasmaexcitation region 112 back into the gas supply region 120, gas inlet116, and RPS unit 114. The operational features may include maintaininga pressure difference between the gas supply region 120 and plasmaexcitation region 112 that maintains a unidirectional flow of plasmathrough the ion suppression element 110. The structural features mayinclude the selection of dimensions and cross-sectional geometry of theholes 115 in the lid 106 that deactivates backstreaming plasma.

As noted above, the lid 106 and the ion suppression element 110 mayfunction as a first electrode and a second electrode, respectively, sothat the lid 106 and/or ion suppression element 110 may receive anelectric charge. In these configurations, electrical power (e.g., RFpower) may be applied to the lid 106, ion suppression element 110, orboth. For example, electrical power may be applied to the lid 106 whilethe ion suppressor 110 is grounded. The hybrid plasma processing system100 may include a RF generator 140 that provides electrical power to thelid 106 and/or ion suppression element 110. The electrically charged lid106 may facilitate a uniform distribution of plasma (i.e., reducelocalized plasma) within the plasma excitation region 112. To enable theformation of a plasma in the plasma excitation region 112, insulator 108may electrically insulate the lid 106 and the ion suppression element110. Insulator 108 may be made from a ceramic material and may have ahigh breakdown voltage to avoid sparking. If desired, the CCP unit 102may further include a cooling unit (not shown) that includes one or morecooling fluid channels to cool surfaces exposed to the plasma with acirculating coolant (e.g., water).

The ion suppression element 110 may include a plurality of through holes122 (better seen in FIG. 2) that further suppress the migration ofionically-charged species out of the plasma excitation region 112 whileallowing uncharged neutral or radical species to pass through the ionsuppression element 110 into an activated gas delivery region 124 (FIG.2). These uncharged species may include highly reactive species that aretransported with less reactive carrier gas through the holes 122.Therefore, the migration of ionic species through the holes 122 may bereduced, and in some instances completely suppressed. Controlling theamount of ionic species passing through the ion suppression element 110provides increased control over the gas mixture brought into contactwith the underlying wafer substrate, which in turn increases control ofthe deposition and/or etch characteristics of the gas mixture. Forexample, adjustments in the ion concentration of the gas mixture cansignificantly alter its etch selectivity (e.g., SiOx:SiNx etch ratios,Poly-Si:SiOx etch ratios, etc. as discussed above). It can also shiftthe balance of conformal-to-flowable of a deposited dielectric material.

The plurality of holes 122 may be configured to control the passage ofthe activated gas (i.e., the ionic, radical, and/or neutral species)through the ion suppression element 110. For example, the aspect ratioof the holes (i.e., the hole diameter to length) and/or the geometry ofthe holes may be controlled so that the flow of ionically-chargedspecies in the activated gas passing through the ion suppression element110 is reduced. The holes 122 in the ion suppression element 110 mayinclude a tapered portion that faces the plasma excitation region 112,and a cylindrical portion that faces a gas distribution plate orshowerhead 104. The cylindrical portion may be shaped and dimensioned tocontrol the flow of ionic species passing to the showerhead 104. Anadjustable electrical bias may also be applied to the ion suppressionelement 110 as an additional means to control the flow of ionic speciesthrough the ion suppression element 110.

The showerhead 104 is positioned between the ion suppression element 110of the CCP unit 102 and a gas reaction region 130 (i.e., gas activationregion) that makes contact with a substrate that may be placed on apedestal 150. The gases and plasma excited species may pass through theion suppression element 110 into an activated gas delivery region 124that is defined between the ion suppression element 110 and theshowerhead 104. A portion of these gases and species may further passthrough the showerhead 104 into a gas reaction region 130 in which thesubstrate is disposed.

In one embodiment shown in FIG. 1, the showerhead 104 may be a dual-zoneshowerhead that has a first set of channels 126 to permit the passage ofplasma excited species coming from the plasma excitation region 112, anda second set of channels 128 that deliver a second gas/precursor mixtureinto the gas reaction/activation region 130. The first set of channels126 may traverse the thickness of the showerhead 104. Each channel ofthe first set of channels 126 may have an opening facing the gasreaction/activation region 130, and the opening may have a smallerdiameter than the diameter of the channel 126. The second set ofchannels 128 in the showerhead 104 may not traverse the thickness of theshowerhead 104. Therefore, the second set of channels 128 are not influid communication with the plasma excitation region 112. Instead, thesecond set of channels 128 are fluidly coupled to a source gas/precursormixture (not shown) that is selected for the process to be performed.For example, when the hybrid plasma processing system 100 is configuredto perform a deposition of a dielectric material such as silicon dioxide(SiOx), the gas/precursor mixture may include a silicon-containing gasor precursor such as silane, disilane, TSA, DSA, TEOS, OMCTS, TMDSO,among other silicon-containing materials. This mixture is provided tothe second set of channels 128 and then the gas reaction region 130where the mixture is reacted with an oxidizing gas mixture that mayinclude plasma excited species, such as plasma generated radical oxygen(O), activated molecular oxygen (O₂) and ozone (O₃), among otherspecies. Excessive ions in the plasma excited species may be reduced asthe species move through the holes 122 in the ion suppression element110, and reduced further as the species move through the first set ofchannels 126 in the showerhead 104.

In another example, when the hybrid plasma processing system 100 isconfigured to perform an etch on the substrate surface, the sourcegas/precursor mixture may include etchants such as oxidants, halogens,water vapor and/or carrier gases that mix in the gas reaction region 130with plasma excited species distributed from the first set of channels126 in the showerhead 104

The two sets of channels 126, 128 prevent the plasma excited species andsecond gas/precursor mixture from combining until they reach the gasreaction region 130. In some embodiments, one or more of the holes 122in the ion suppression element 110 may be aligned with one or more ofthe first set of channels 126 in the showerhead 104 to allow at leastsome of the plasma excited species to pass through a hole 122 and achannel 126 without altering their direction of flow. In someembodiments, the second set of channels 128 may have an annular shape atthe opening facing the gas reaction region 130, and these annularopenings may be concentrically aligned around the circular openings ofthe first set of channels 126.

The hybrid plasma processing system 100 also includes a pedestal 150that is operable to support and move the substrate (e.g., a wafersubstrate). The distance between the pedestal 150 and the showerhead 104help define the gas reaction region 130. The pedestal may be verticallyor axially adjustable within the processing chamber 100 to increase ordecrease the gas reaction region 130 and effect the deposition oretching of the wafer substrate by repositioning the wafer substrate withrespect to the gases passed through the showerhead 104. The pedestal 150may have a heat exchange channel through which a heat exchange fluid(e.g., water) flows to control the temperature of the wafer substrate.Circulation of the heat exchange fluid allows the substrate temperatureto be maintained at relatively low temperatures (e.g., about −20° C. toabout 90° C.). The pedestal 150 may also be configured with a heatingelement (such as a resistive heating element) embedded therein tomaintain the substrate at desired heating temperatures (e.g., about 90°C. to about 1100° C.).

Embodiments of the disclosure illustrated in FIGS. 1 and 2 provide ahybrid plasma processing system incorporating a RPS unit 114 with a CCPunit 102 for substrate processing. By combining a RPS unit 114 with aCCP unit 102, the plasma excited species may be generated by the CCPunit 102 alone, the RPS unit 114 alone, or both. The CCP unit 102 mayserve as a primary plasma source while the RPS unit 114 may serve as asecondary plasma source, or vice versa, depending upon the processscheme. In cases where the process requires higher power input (550 W orabove), both CCP unit 102 and RPS unit 114 may be used to generateplasma excited species so that some power burden is shifted from the CCPunit 102 to the RPS unit 114, which allows the CCP unit 102 to operateat lower power, thereby reducing ion bombardment of the poweredelectrode in the CCP to a lesser extent. As a result, particlecontamination of the substrate surface due to ion bombardment of theprotective coating layer on the powered electrode of the CCP unit 102 isreduced.

FIG. 3 shows a simplified schematic 300 of the gas flow paths of a pairof gas mixtures through the hybrid plasma processing system 100 of FIG.1 according to embodiments of the disclosure. At block 305, a first gas,such as a plasma generating gas mixture, is supplied to a CCP unit 102via a gas inlet 107. An exemplary first gas may include one or more ofthe following gases: CF₄, NH₃, NF₃, Ar, He, H₂O, H₂, O₂, etc. At block310, the first gas may be excited through a plasma discharge within theplasma excitation region 112 of the CCP unit 102 to form one or moreplasma effluents. Alternatively (or in addition to the primary plasmageneration within the CCP unit 102), a remote plasma system (RPS) unit114 coupled to the hybrid plasma processing system 100 may be turned onto generate a secondary plasma (from a second gas source) whose plasmaexcitation products, which may introduce into the plasma excitationregion 112 through the gas inlet 116, or flow through or bypass the CCPunit 102 and to the gas reaction region 130 downstream the CCP unit 102through the first set of channels 126 in the showerhead 104. The RPSplasma excitation products may include ionically-charged plasma speciesas well as neutral and radical species. The plasma generating gasmixture flowing to the CCP unit 102 may be the same or different thanthe plasma generating gas mixture flowing to the RPS unit 114. In anycases, the RPS and CCP plasma source should be turned on in anappropriate sequence, either through the process receipt or hardwaretuning, to avoid crosstalk between two sources and lost of power, whichmay potentially damage the chamber parts/substrate.

As noted above, in cases where RPS plasma excitation products flowthrough the CCP unit 102 to prevent the mixing of RPS plasma excitationproducts with the plasma effluents within the plasma excitation region112 from happening very upstream (to enhance the lifetime of the plasmaspecies), the CCP unit 102 may be turned on with small amount of powerto boost radical regeneration to compensate loss due to the flow path,or change radical composition by using different RF frequency and otherparameters to react with the plasma effluents within the plasmaexcitation region 112, thus providing extra process tuning knobs.

At block 315, whether the plasma effluents are generated by the CCP unit102, the RPS unit 114, or both, they may be passed through an ionsuppression element 110 in the CCP unit 102. The ion suppression element110 may block and/or control the passage of ionic species while allowingthe passage of radical and/or neutral species as the plasma activatedfirst gas travels to the gas reaction region 130 in the hybrid plasmaprocessing system 100. At block 320, a third gas may be optionallyintroduced into the hybrid plasma processing system 100 to the gasreaction region 130 through the second set of channels 128 in theshowerhead 104. As noted above, the contents of the third gas may varydepending on the process performed. For example, the third gas mayinclude hydrogen, helium, argon or any deposition compounds (e.g.,Si-containing compounds) for deposition processes and etchants for etchprocesses. Contact and reaction between the first, second and thirdgases may be prevented until the gases arrive at the gas reaction region130 of the hybrid plasma processing system 100.

One way to prevent the first, second and third gases from interactingbefore the gas reaction region is to have them flow though separatechannels in a dual-zone showerhead 104. At block 330, the activatedfirst gas (and activated second gas from RPS, if used) flows through afirst set of channels 126 in the showerhead 104 without interacting withthe third gas that passes through a second set of channels 128. At block335, after exiting the showerhead 104, the activated first gas (andactivated second gas from RPS, if used) and third gases may mix togetherin the gas reaction region 130 of the hybrid plasma processing system100. Depending on the process performed, the combined gases may react todeposit a material on the exposed surfaces of the substrate, etchmaterials from the substrate, or both.

In any of the embodiments discussed throughout this disclosure, eitherthe RPS or the RF plasma can be used as primary or secondary radicalsource for substrate processing depending on process requirements. RPScan be placed further away from the substrate processing area whereasthe other RF plasma source can be placed very close to wafer processingarea. For certain process gases, RPS has shown great productivity andreliability performance; however, the same process gases may exert greatburden to other RF plasma source, causing productivity and reliabilityissue, such as defectively and parts degradation. In the presence ofsuch gases, RPS can be used as the primary source for radicals, and RPSradical flow can flow through or bypass the RF plasma source. In thecase of RPS flow through RF plasma source, the RF plasma source can beturned on with small amount power to boost radical regeneration tocompensate loss from the flow path, or to change radical composition byusing different RF frequency and other parameters, thus provide extraprocess tuning knobs. At the meantime small power can sustain the RFplasma source part condition. For process gases which need to bedisassociated close to the substrate, RF plasma source may be theprimary source for substrate processing, and the disassociated gases canbe delivered to the substrate level efficiently.

FIG. 4 is a simplified cross-sectional view of an exemplary hybridplasma processing system 400 showing an exemplary gas flow in bold linesaccording to embodiments of the disclosure. The hybrid plasma processingsystem 400 includes a remote plasma source (RPS) unit 414 shared by atandem processing chamber 446, 448. The hybrid plasma processing system400 may have a housing 408 covering a respective one of the tandemprocessing chambers 446, 448. The processing chambers 446, 448 may bepositioned adjacent to each other in a symmetrical or asymmetricalmanner. The RPS unit 414 may be disposed at any location on the housing408 for ease of sharing RPS plasma excitation products between thetandem processing chambers 446, 448. Each of the tandem processingchambers 446, 448 has its own capacitively coupled plasma (CCP) unit402, which includes a lid 458 (i.e., top electrode) and an ionsuppression element 410 (i.e., bottom electrode). The ion suppressionelement 410 and a showerhead 404 disposed relatively below the CCP unit402 may be coupled to an electrical power (e.g., RF power) 460.Generally, the tandem processing chambers 446, 448 are substantiallyidentical to the hybrid plasma processing system 100 shown in FIGS. 1and 2 except that gas inlet 407 is modified to receive plasma excitationproducts from the RPS unit 414 while the gas inlet 416 is modified toreceive a first gas from a gas source 450.

A first gas, such as a plasma generating gas mixture discussed abovewith respect to FIGS. 1-3, may be supplied from the gas source 450 tothe CCP unit 402 via a gas inlet 416. The first gas is then excitedthrough a plasma discharge within the plasma excitation region 412 ofthe CCP unit 402 to form one or more plasma effluents. In oneembodiment, the gas inlet 416 may be disposed in the center of the lid458 and surrounded by a plurality of holes 456 distributed between thecenter and edge of the lid 458. The holes 456 are used to introduce RPSplasma excitation products into the plasma excitation region 412. Thenumber of the holes 456 may be between about 100 and about 5000. Theholes 456 may be configured to block ions and allow only the radicals inthe RPS plasma excitation products to go through by controlling thehole's aspect ratio and the size of hole in terms of the diameter andlength. As noted above, the gas inlet 416 and holes 456 may beconfigured and arranged to modulate the flow between the center and theedge within the plasma excitation region 412 in a desired manner (i.e.,controlling the center-to-edge distribution) to tune the filmuniformality on the substrate.

The RPS unit 414 may include a tube 417 where a plasma of ions,radicals, and electrons is generated. The tube 417 may have a gas inlet419 disposed at one end of the tube 417 and a gas outlet 421 disposed atthe other end of the tube 417 opposing the gas inlet 419. The gas inlet419 is coupled to a gas source 423 while the gas outlet 421 is in fluidcommunication with the plasma excitation region 412 of the CCP unit 402in each of the tandem processing chambers 446, 448. The RPS unit 414 maybe coupled to an energy source (not shown) to provide an excitationenergy, such as an energy having a microwave frequency, to the RPS unit414 to excite the process gas from the gas source 423 into a plasma. TheRPS plasma excitation products are introduced from the RPS unit 414 tothe processing chambers 446, 448 via respective gas passageways 452,454. The gas passageways 452, 454 are in fluid communication with thegas inlet 407, which disperses RPS plasma excitation products into theplasma excitation region 412 through the holes 456 formed in a lid 458.The plasma generating gases from the RPS unit 414 may be used to strikea plasma in the plasma excitation region 412, or may maintain a plasmathat has already been formed in the plasma excitation region 412 asdiscussed above.

In some embodiments, the plasma generating gases from the RPS unit 414and/or the plasma effluents from the CCP unit 402 may flow through holes462 in the ion suppression element 410 and then a first set of channels426 in a showerhead 404 and into a gas reaction region 430. As discussedabove, the RPS plasma excitation products may or may not react with theplasma effluents (from the CCP unit 402) generated within the plasmaexcitation region 412. In cases where the RPS plasma excitation productsflow through CCP unit 402, the CCP unit 402 may be turned on with smallamount of power to boost radical regeneration to compensate loss due tothe flow path, or change radical composition by using different RFfrequency and other parameters to react with the plasma effluents withinthe plasma excitation region 412 as discussed above with respect to FIG.3. In the meantime, the small power can sustain the RF plasma sourcecondition.

In some embodiments, a second gas may be optionally introduced into asecond set of channels 428 in the showerhead 404 from a gas source 464.The second set of channels 428 flow the second gas into the gas reactionregion 130 through the second set of channels 128 in the showerhead 104.As noted above, the contents of the second gas may vary depending on theprocess performed. The plasma effluents from the CCP unit 402 and secondgases (and RPS plasma excitation products from the RPS unit 414 if used)may mix together in the gas reaction region 130 within each of thetandem processing chamber 446, 448. Depending on the process performed,the combined gases may react to deposit a material on the exposedsurfaces of the substrate, etch materials from the substrate, or both.

In some alternative embodiments, instead of sharing the same RPS unit414, each of processing chambers 446, 448 may each has its own remoteplasma source (RPS) unit disposed external to the processing chamber446, 448. In some aspects, the gas source of the RPS unit for theprocessing chamber 446 and the gas source of the RPS unit for theprocessing chamber 448 may or may not be the same.

While the CCP unit is illustrated as an example for the RF plasma sourcein this disclosure, the disclosure contemplates any plasma source usinglow-pressure discharge such as inductively coupled plasma (ICP) source,or using atmospheric pressure discharge such as capacitive discharge, orany other suitable plasma source can be used interchangeably inembodiments described herein. In any cases, either the RPS or the RFplasma (or any other type of plasma source) can be used as primary orsecondary radical source for substrate processing depending upon theprocess requirements. For process gases which need to be disassociatedclose to the substrate, the RF plasma source may be used as the primarysource for substrate processing so that the disassociated gases can bedelivered to the substrate level efficiently.

In summary, embodiments of the disclosure provide a hybrid plasmaprocessing system incorporating a RPS unit with a CCP unit for substrateprocessing. By combining a RPS unit with a CCP unit, the plasma excitedspecies (particularly neutral and radical species) may be generated bythe CCP unit alone, the RPS unit alone, or both. The CCP unit may serveas a primary plasma source while the RPS unit may serve as a secondaryplasma source, or vice versa, depending upon the process scheme. Incases where the process requires higher power input (550 W or above),both CCP unit and RPS unit may be used to generate plasma excitedspecies so that some power burden is shifted from the CCP unit to theRPS unit, which allows the CCP unit to operate at lower power, therebyreducing ion bombardment of the powered electrode in the CCP to a lesserextent. As a result, particle contamination of the substrate surface dueto ion bombardment of the protective coating layer on the poweredelectrode of the CCP unit is reduced.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A substrate processing system, comprising:a tandem processing chamber, comprising: a first processing chamber,comprising: a first lid having a first gas inlet and a plurality offirst holes surrounding the first gas inlet, wherein the first gas inletis in fluid communication with a first gas source; a first substratesupport arranged parallel to the first lid; a first ion suppressionelement arranged parallel to the first lid, wherein the first ionsuppression element and the first lid define a first plasma excitationregion between the first lid and the first substrate support; and afirst gas distribution plate disposed between the first ion suppressionelement and the first substrate support, wherein the first gasdistribution plate and the first substrate support define a firstsubstrate processing region within the first processing chamber; and asecond processing chamber disposed adjacent to the first processingchamber, the second processing chamber comprising: a second lid having asecond gas inlet and a plurality of second holes surrounding the secondgas inlet, wherein the second gas inlet is in fluid communication withthe first gas source; a second substrate support arranged parallel tothe second lid; a second ion suppression element arranged parallel tothe second lid, wherein the second ion suppression element and thesecond lid define a second plasma excitation region between the secondlid and the second substrate support; and a second gas distributionplate disposed between the second ion suppression element and the secondsubstrate support, wherein the second gas distribution plate and thesecond substrate support define a second substrate processing regionwithin the second processing chamber; and a remote plasma source (RPS)unit coupled to the tandem processing chamber, the RPS unit having a gasinlet and an gas outlet, wherein the gas inlet is in fluid communicationwith a second gas source, and the gas outlet is in fluid communicationwith the plurality of the first holes and the plurality of the secondholes through a first gas passageway and a second gas passageway,respectively.
 2. The system of claim 1, wherein the plurality of firstholes and the plurality of second holes are configured to distributeplasma excitation products from the RPS unit to the plasma excitationregion.
 3. The system of claim 1, wherein the first and second ionsuppression elements each has a plurality of through holes configured toallow only uncharged neutral or radical species to pass through.
 4. Thesystem of claim 3, wherein each of the through holes of the first andsecond ion suppression elements includes a tapered portion facing therespective plasma excitation region and a cylindrical portion facing therespective gas distribution plate.
 5. The system of claim 1, wherein thefirst and second gas distribution plates each have: a first set ofchannels configured to traverse the thickness of the respective gasdistribution plate to permit passage of plasma excited species from theplasma excitation region; and a second set of channels configured todeliver a gas mixture from a third gas source to the respectivesubstrate processing region, wherein the second set of channels is notin fluid communication with the respective plasma excitation region. 6.The system of claim 5, wherein the first set of channels in the firstand second gas distribution plates is in fluid communication with therespective plasma excitation region and the RPS unit.
 7. The system ofclaim 1, wherein the first and second lids and the first and second ionsuppression elements are coated with a protective layer comprisingalumina or yttrium oxide.
 8. A substrate processing system, comprising:a housing covering a tandem processing chamber, the tandem processingchamber comprising: a first processing chamber coupled to a first plasmasource, the first processing chamber having a first substrate processingregion; and a second processing chamber disposed adjacent to the firstprocessing chamber, the second processing chamber coupled to a secondplasma source and having a second substrate processing region; and aremote plasma source (RPS) unit disposed on the housing, the RPS unithaving a gas inlet and an gas outlet, wherein the gas inlet is in fluidcommunication with a first gas source, and the gas outlet is in fluidcommunication with the first substrate processing region and the secondsubstrate processing region, respectively, wherein the first processingchamber further comprises: a first plasma excitation region definedbetween a first top perforated plate and a first bottom perforatedplate, wherein the first bottom perforated plate is configured to allowonly uncharged neutral or radicals to pass through; and a first gasdistribution plate disposed between the first bottom perforated plateand a first substrate support, wherein the first gas distribution plateand the first substrate support define the first substrate processingregion within the first processing chamber, and the first substrateprocessing region is in fluid communication with the first plasmaexcitation region through the first gas distribution plate.
 9. Thesubstrate processing system of claim 8, wherein the first gasdistribution plate is fluidly connected to a second gas source that isthe same or different than the first gas source.
 10. The substrateprocessing system of claim 8, wherein the second processing chamberfurther comprises: a second plasma excitation region defined between asecond top perforated plate and a second bottom perforated plate,wherein the second bottom perforated plate is configured to allow onlyuncharged neutral or radicals to pass through; and a second gasdistribution plate disposed between the second bottom perforated plateand a second substrate support, wherein the second gas distributionplate and the second substrate support define the second substrateprocessing region within the second processing chamber, and the secondsubstrate processing region is in fluid communication with the secondplasma excitation region through the second gas distribution plate. 11.The substrate processing system of claim 10, wherein the second gasdistribution plate is fluidly connected to a second gas source that isthe same or different than the first gas source.
 12. The substrateprocessing system of claim 8, wherein the first primary plasma sourceunit is a capacitively coupled plasma (CCP) unit, an inductively coupledplasma (ICP) source, or a plasma source using low-pressure oratmospheric pressure discharge.
 13. The substrate processing system ofclaim 8, wherein the second plasma source unit is a capacitively coupledplasma (CCP) unit, an inductively coupled plasma (ICP) source, or aplasma source using low-pressure or atmospheric pressure discharge. 14.The substrate processing system of claim 8, wherein the gas outlet isconfigured to allow only radicals to pass through.